This study investigated whether the males of the Tengmalm’s owl change their activity patterns, evaluated based on delivering prey to nestlings in respect of different food supply. During two breeding seasons 12 owl nests were continuously monitored by a camera system to obtain data on the time of male prey delivery and identification of prey items brought to nestlings. Even though the abundance of food supply differed in both years, there was no difference in the number of prey items delivered by males to their nests. Nevertheless, the species composition of food supply as well as the species composition of prey delivered by males to the nests differed between 2004 and 2006. Yet male activity patterns were the same in both years; they showed a monophasic cycle with one peak at the beginning of the night, around 22:00 and 23:00. Moreover, the males delivered prey to their chicks strictly at night time in both years and they started (the first evening arrival at the nest) and ended (the last morning arrival at the nest) their nest visiting in the same time in 2004 and 2006. The results of this study suggest that activity patterns of Tengmalm’s owl males in central Europe do not depend on varying food conditions.
In birds of prey, food availability affects the entire breeding process, including reproductive success. Sequential polyandry, sometimes documented in raptors and owls, has been observed occasionally in Tengmalm’s owl in years of high food availability. In this study, the effect of food supply on the reproductive strategy of the central european Tengmalm’s owl population has been investigated. The availability of the main prey of owls was significantly below average in the study year 2014. This resulted in low breeding density of owls, delayed egg laying, small clutch sizes, and low reproductive success. Nevertheless, successful sequential polyandry of one Tengmalm’s owl female was recorded during the breeding season. The polyandrous female laid four eggs in each nests, and 50 % and 75 % of four hatched nestlings left the nest during the first and second breeding, respectively. In both nesting attempts, the two-year old female was of a substandard body mass and she abandoned the fledglings before they left the nests. Prey delivered by males to both nests was comprised mainly of alternative prey (birds and shrews). The results of this study suggest that there are probably some other factors, in addition to food availability, that may play a role in Tengmalm’s owl’s decisions in matters of parental care.